It is estimated that 90% of all machine bearings are lubricated by grease. While oil analysis is a widespread tool for monitoring bearing and lubricated component health of important oil lubricated equipment, grease analysis is not generally adopted in a similar manner for important grease lubricated machines. Analyzing a sample of grease taken from a grease-lubricated bearing sometimes is performed to pinpoint the cause of bearing problems in failure analysis. However, the ability to adopt regular and routine grease analysis for important machines has been historically limited by the inability to easily obtain representative samples of the grease in a sufficient quantity to perform cost-effective and meaningful analysis.
Some machine bearings, such as pillow block bearings, may be located on the outside of the machine and may have an exposed layer or thickness of grease surrounding the bearing. A grease sample is obtained by scooping or scraping through the layer of grease. The grease nearest the bearing usually makes the most representative sample, and the scoop or scraper is manipulated to retrieve grease near the bearing. The grease sample, however, may be contaminated by grease retained by the scoop or scraper when moving through the layers of grease away from the bearing.
Other machine bearings may be located in areas of the machine that have limited access. This can make it difficult to manipulate a scoop or scraper in such away as to obtain only an uncontaminated grease sample taken near those surfaces.
Some machine bearings are housed inside the machine without external access. The housing may incorporate grease inlet openings and grease drain openings associated with the machine bearings. Historically, some efforts to obtain grease samples have been made by flowing fresh grease into a grease inlet until grease flows out a drain outlet. While this can sometimes be effective, there is a risk that the bearing may be overfilled with grease—damaging the bearing or lifting the bearing seals.
Thus there is a need for grease sampling devices that can obtain a representative grease sample from a bearing, gear or other internally mounted grease lubricated component. The devices should be usable in different bearing operating configurations for retrieving samples from exposed bearings, from bearings having limited access, or from bearings or other lubricated parts accessible via machine openings.